Patent Documents 1, 2 disclose a quantum cell that is an all-solid-state physical secondary cell. The quantum cell disclosed in Patent Document 1 has a structure that a first electrode layer, an n-type metal oxide semiconductor layer, a charging layer, a p-type metal oxide semiconductor layer, and a second electrode layer are layered on a substrate. The charging layer is a layer capable of capturing electrons obtained through photoexcited structural change caused on a particle-like n-type metal oxide semiconductor that is covered with an insulating material.
In the disclosure of Patent Document 1, a plurality of quantum cells are connected in series to increase a terminal voltage or connected in parallel to increase current capacity. Further, Patent Document 2 discloses a method and an apparatus to measure charging-discharging characteristics and electrical characteristics of a quantum cell.